ROME, Nov. 3 (Xinhua) -- The strongest earthquake that hit central Italy last Sunday caused a "step" stretching at least 15 km between Arquata and Ussita, two towns in the quake area, the National Institute for Geophysics and Volcanology (INGV) said Thursday.
The step "carved" into Mt.Vettore had an average height ranging between 20 and 70 cm and in some points was higher than one meter, INGV said.
Such a phenomenon, also called "faultline shoeprint", is quite common for quakes of a magnitude close to 6.0 and "represents the continuation towards the surface of the rupture and the slide that happened in the faultline at a great depth", according to INGV.
The Oct. 30 quake of 6.5-magnitude was the latest of four major tremors that struck central Italy.
On Aug. 24, a quake of 6.0-magnitude in the same area left 298 dead, hundreds injured and thousands homeless.
On Oct. 26, two earthquakes jolt the central areas without causing deaths, but leaving many buildings damaged or even destroyed.
So far, Italy's civil protection department has been "assisting" over 28,000 displaced people after the earthquakes in central Italy since Aug. 24.
"More than 19,000 were being helped in their home towns and villages, and some 8,400 had been accommodated in hotels on the Adriatic coast," said the civil protection department. About 500 people are still in tents in Lazio, Marche and Umbria, the regions experienced the damages from the waves of earthquake.
In another development, a report presented Thursday by Italian environmental association Legambiente said some 90 percent of Italian schools have not been built with modern anti-seismic criteria.
According to Legambiente, 65.1 percent of school buildings were built before anti-seismic building legislation came into effect in 1974 and 90.4 percent before a law on energy efficiency in 1991.
Only one in two schools in Italy has been certified to be up to anti-seismic code, according to the report titled "school ecosystem", which was presented in Rome during a forum on the school construction industry.
Earlier on Thursday, Italian Premier Matteo Renzi said his government would not let European Union budget rules stop its efforts to make sure Italian buildings are seismic proof. "It's unthinkable that schools should collapse for European stability," Renzi was quoted as saying by ANSA.
